Some aspects of modelling scallop (Pecten maximus, L.) dredge efficiency and special reference to dredges with depressor plate (English Channel, France)

摘要

To estimate the abundance of scallop populations either by VPA approach or by directed survey on seabeds it is necessary to evaluate the efficiency of fishing gears. The age-size structure of commercial or experimental catches does not usually correspond to that of the targeted population. Several previous studies on scallop stocks in Scottish or English Channel waters show that different functions can be fitted on relationships of dredge efficiency versus scallop size (monotonic increasing functions or curves including increasing and decreasing stages). The two ways to tackle the question involve to calculate efficiency estimates, absolute (by diving after dredge haul) or relative (by comparing two different parameter dredges in standardized sampling conditions). This study develops aspects of methodology applied on calculation of dredge efficiency parameters. The study focuses on data of English Channel French scallop fisheries. [References: 48]